Bathing appliances such as hot tubs, swimming pools, shower units and hydromassage bath fixtures often employ a means of detecting the level of water in the appliance to prevent flooding, operation with insufficient water or damage to plumbing and piping components. Likewise, bathing water temperature measuring probes prevent scalding, freeze protection and promote proper water chemistry.
Prior art water detection and temperature probes are known to be simple devices which require invasive mounting and direct contact with the circulating water. These issues complicate installation, service removal, lower life due to corrosive action with water and potentially create a shock hazard for the bathing user.
Another known system includes the non-invasive, capacitive water detection probe. Such probes eliminate the need for the water detecting elements to be in contact with the water. Such systems employ an apparatus which is capable of detecting changes in dielectric capacitance through a non-metallic vessel. This system measures the dielectric constant of a material. For example, a bath tub which is empty contains relatively dry air, which has a dielectric constant of approximately 2-5. When the bath is filled with water, the dielectric constant changes to approximately 80.
Although these detectors can be fabricated for reasonable cost, they still require fault prone cabling to provide a signal path to a control system. In addition, there is no similar method of measuring water temperature therefore, invasive, in-the-water temperature sensing is considered state of the art. As water level and water temperature detecting are often utilised together, there is little reason to install non invasive capacitance water level sensing with an invasive water temperature sensor.
Accordingly, it is an object of the present invention to provide an improved means of capacitive water level detection and water temperature sensing without an invasive mounting means, such that both water level and water temperature can be sensed through the bathing appliance vessel.
It is a further object of the present invention to eliminate the interconnection cables and associated wiring used in the prior art. The present invention contemplates using an ultra-low power radio transmission signal to provide water level and temperature telemetry data to the controller means.
It is a further object of the present invention to provide a water level and water temperature sensor that is safely operable by a bather immersed in water, creating an electrically safe installation in a wet, electrically hazardous bathing environments.
It is a further object of the present invention to provide a water level and water temperature sensor that utilises very low current consumption from the installed battery, such that battery life is extended to a long a period as possible.